$76 (P1739) - Power-Up at Speed

Name Of Code: $76 (P1739) - Power-Up at Speed

When Monitored: When the TCM (Transmission Control Module) initially powers-up.

Set Condition: If the TCM powers up while in the "Drive" position and the vehicle is going above 20 MPH, the code is set.

Theory of Operation: If a vehicle loses power to the TCM, the vehicle will go to the 2nd gear mode since there is no power available to control the transmission solenoids. However if power is restored, the TCM will power-up and normal operation will be restored.

New for 97MY is a new fault code 76 that identifies that power to the TCM was restored when the gear selector was in a "Drive" position while the vehicle was moving at speeds above 20 MPH. Unfortunately, if a person shifts to Neutral and cycles the ignition key and quickly shifts to "Drive" while moving before the TCM comes out of its START ROUTINE, the fault can be set. Therefore it is critical that this fault diagnosis repair procedure should only be used if the vehicle is experiencing intermittent 2nd gear operation and subsequently a return to normal operation during normal driving.

Transmission Effects: No limp-in condition. Fault code is for information only when trying to diagnosis intermittent 2nd gear operation and subsequently a return to normal operation.

Possible Causes:
- No Problem if vehicle is started in "neutral" at speeds above 20 MPH and shifted quickly to "Drive" before TCM comes out of the START ROUTINE.

FOR INTERMITTENT 2ND GEAR OPERATION AND THEN A SUBSEQUENT RETURN TO NORMAL OPERATION WITHOUT CYCLING THE IGNITION KEY
- Intermittent Direct Battery connection between TCM (60-way pin 56) and battery.
- Intermittent Fused Ignition Switch Output between TCM (60-way pin 11) and ignition switch.
- Intermittent Ground to TCM (60 way pins 53 and 57).